This is a sturdy cup holder for large yeti cup (tested with 30 and 40oz).
I couldn't find a sturdy holder that mounts vertically to a frame. It was designed for 3/4 inch bed frame. As pictured, I printed it with wood PLA and stained. This cup holder does not have a bottom so it only works with solid tapered cups.
Here is the 3D Mars wood filament i used on Amazon: https://goo.gl/qughJa
Update 11/10/18: rebuilt the part in Solidworks, refined the design a bit, smoothed out the edges, tapered the hold cutout to be more user friendly and universal. Included Solidworks and STL.
The top of the cup holder prints flat on the bed. No supports needed.